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Here, we sought to reconstruct the Pleistocene and Holocene evolution of Cartagena Bay. Therefore, 16 borehole cores were analysed with the following aims: (1) to define a chronological framework; (2) to obtain data on the palaeoenvironment; and (3) to establish the relationship with human activities, especially focused on the reconstruction of the Carthago Nova (also known as Qart Hadasht) conquest. A total of 147 samples were recovered for amino acid racemisation (AAR) dating; 32 for radiocarbon dating (14C); and 159 for sedimentological, palaeontological, and biomarker determination. These approaches allowed us to elucidate the evolutionary phases of the palaeolandscape in Cartagena. The simultaneous use of AAR and 14C dating allowed the discrimination of spurious ages and the establishment of a chronological scale. During the Marine Isotope Stages (MIS) 7 and 5, the sea level (SL) in Cartagena Bay was almost the same as today. An alluvial plain developed in the northern area, and a delta was formed by an ephemeral river. In contrast, during MIS4, after a fall in SL, a wide sandy coastal plain emerged, leading to the accumulation of colluvial and aeolian deposits. The Holocene transgression was reflected in the hinterland in a late and temporarily floodable marsh fed by alluvial fans and creeks, producing a salinity gradient from freshwater to brackish and saline waters. Along the sea front, the marine influence was evident but not dominant, grading up and landwards to saline and freshwater marshes. Therefore, at the time of Scipio's conquest, the geography of Carthago Nova was quite different from that described by Polybius. The Roman's sudden attack seized Qart Hadasht from the south-west, avoiding the marshy area and not crossing a fast and deep ebb stream as it never existed on the Mediterranean Iberian coast. [ABSTRACT FROM AUTHOR]

Here we reconstructed the evolution of the Mazarrón Basin during the Pleistocene and Holocene. In this regard, we studied 9 cores with the aim to: 1) define a chronological framework; 2) obtain data on the palaeoenvironment; and 3) establish the relationship with recent tectonics. A total of 158 samples were recovered for amino acid racemization (AAR) dating, 4 for radiocarbon dating (14C), and 332 for sedimentological and palaeontological determination, and 110 for determination of the mineralogical content. These approaches allowed us to elucidate the evolutionary phases of the palaeo-landscape of the Mazarrón Basin, a fault-controlled graben affected by diverse faults, mainly those of Las Moreras and Rella. The ages of the records and the facies correlation indicate that Las Moreras Fault controlled sedimentation during Marine Isotope Stage (MIS) 7, whereas the Rella Fault was strongly active during the Middle Holocene. During MIS7, a brackish lagoon developed in the western area, overlying alluvial fan deposits. Later, the area was uplifted, thereby becoming exposed to erosion. The activity of the Rella Fault allowed sedimentation in the western part of the Mazarrón Basin during the Middle Holocene, while in the Upper Holocene sedimentation occurred in the eastern part. The Holocene transgression was reflected in a temporarily floodable marsh in the hinterland, with changing salinity conditions, from brackish to euhaline waters. Along the sea front, the marine influence was evident but not dominant. Thus, the Mazarrón Basin during the Holocene was brackish to highly euhaline, with variable biological diversity linked to a narrow and probably discontinuous communication with the sea, with restricted circulation and long flushing times, which was reflected by the significant presence of halite. The record ended with recent alluvial/anthropic sediments. [ABSTRACT FROM AUTHOR]